This invention relates to a rapid, sensitive and specific assay for limonin, allowing the detection and quantification of this most important bitter constituent of citrus juice, e.g. grapefruit juice.
The determination of limonin on a routine basis today is extremely difficult. This compound occurs in very low levels in plant material, and only 5 parts per million of it give grapefruit juice an unacceptably bitter taste. The present conventional analytical methods (thin layer chromatography, high performance liquid chromatography) are very difficult and very slow in determining these low levels of limonin within the high concentrations of contaminants. Normally this requires the preparation of purified and concentrated extracts for analysis. The time required for analysis is one day or even more, which is prohibitive in a quality control procedure.
It is an object of this invention to provide a procedure for a rapid and precise analysis of limonin in unpurified plant extracts (e.g. grapefruit juice) even at exceedingly low levels (down to 1-10 parts per billion). The assay time is short, normally less than one hour.